<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        let arr = [{
            id: 1,
        }, {
            id: 2,
        }];
        let target = arr.find((item, index) => item.id == 1);
        console.log(target);
        let ary = [1, 2, 4, 6];
        let tar = ary.findIndex(item => item > 4);
        console.log(tar);
        var flag = ary.includes(4);
        console.log(flag);
    </script>
</head>

<body>

</body>

</html>